Main Features & Specifications
Can be powered from 9-12V DC or from a USB port (5V).
Two Frequency/Duty Cycle Inputs with frequency up to
Positive Duty Cycle Range: 0-100%.
Four Voltage/Resistance Inputs Plus Battery Voltage (the latter has
its own channel).
Voltage Range: 0-16V (greater or smaller ranges possible by changing
Sensitivity with 16V scale: approx. 16mV.
Best Sensitivity: approx. 5mV (requires changing one resistor and
recalibrating using the supplied PC software).
Two output channels to drive external relays or
Up to 10 displayed variables.
Averaging or direct acquisition mode for each
Screen dimming on ambient light with adjustable sensitivity and
selectable minimum brightness.
7 x 15 dot matrix LED display (scrolling or static
Static display of up to 4 digits (floating point)
Selectable scrolling speed.
On screen limit warnings for each variable in the static display mode.
Software calibration using polynomial interpolation.
Persistent settings stored in non-volatile memory.
Easily load and store previous settings to file on your
Easily load and store different calibration point files on your
All settings changeable using the USB port and PC host
Data logging via the USB port; selectable variable update frequency
from 0.1-8Hz; can collect 1000s of samples to a PC’s hard
So what’s a scrolling display? You really need a short video to
show what this project does. The readout continually "scrolls" from left to
right, displaying one, two and up to 10 computed values from up to six different
signals. Each value is preceded by its description, such as battery voltage,
temperature, duty cycle and so on. If you want to focus on one reading, pressing
the sole pushbutton will make the display static.
Fig.1: block diagram of the Car Scrolling Display. A PIC 18F4550 microcontroller is at the heart of the project. It processes various inputs, drives the dot matrix display, manages the USB connection and drives the two outputs.
Anyway, let’s just give a sample of what this project can
Measure Engine Temperature – have
a relay switch on above a preset
Measure Fuel Injector Duty – have a relay switch if the duty cycle is too high
or too low.
Measure Engine RPM – have a relay switch on at a preset RPM (perhaps
to indicate when to change gear).
Measure Throttle Position and Delta Throttle
Position – if the accelerator pedal
is pressed too abruptly, a relay can be made to switch on this
Measure Speed – have a relay switch if the speed is too high or too
Measure Fuel Tank Level as a percentage of full tank – have a relay switch
on or off if the level is too high or too low.
Measure Battery Voltage – have a relay switch on if the voltage is too high
or too low.